There are various techniques and uses in which metal substances are deposited on substrates. In various such methods, the metal to be deposited is provided in a form of a soluble complex or molecule, e.g. in an aqueous solution. Under appropriate conditions the complex or molecule is reduced and deposits the metal onto the substrate.
At times, in order to ensure deposition of metal from solution onto a substrate, it is preferable to first provide nucleation centers on the substrate. Such nucleation centers may, for example, be a variety of metal complexes, clusters or small metal particles, deposited on or attached to the surface.
Examples of techniques involving metal deposition are a variety of image formation or latent image contrast-enhancement techniques for photography, optical microscopy or electron microscopy. Another example of laboratory techniques where metal complexes are deposited onto a substrate, is in imaging of separation products, e.g. proteins or nucleic acids, in a variety of chromatographic or electrophoretic techniques.
The metal most typically used in such techniques is silver. However, one typical drawback of silver deposition is that the deposition is not completely specific and some degree of spontaneous deposition of silver may occur also without an a priori deposition of nucleation centers. Thus, where silver deposition is used in image-enhancement or contrast-enhancement methods, there is typically a limited signal-to-noise ratio.